Molded foam

ABSTRACT

A molded foam is provided in which even when a force in a sliding direction is applied to another member in contact with its surface, the occurrence of a shift in position relative to the other member can effectively be prevented and the occurrence of unusual noise due to rubbing between its surface and the other member can effectively be prevented. The molded foam is formed by heating expandable resin particles filled into a foaming mold. The molded foam has a plurality of first ridges arranged in one direction and a plurality of second ridges arranged in another direction and disposed so as to intersect the first ridges, the first and second ridges being provided on the surface of the molded foam.

TECHNICAL FIELD

The present invention relates to a molded foam formed by heatingexpandable resin particles filled into a foaming mold.

BACKGROUND ART

In general, a molded foam is manufactured by a manufacturing methoddescribed below. First, resin particles are preliminarily foamed toobtain expandable resin particles. Next, the obtained expandable resinparticles are filled into a foaming mold (hereinafter, referred to as a“mold”). The expandable resin particles filled into the mold are againfoamed by being heated with steam, thereby forming a molded foam. Theformed molded foam is cooled in the mold by using cooling water or thelike. The cooled molded foam is released from the mold, thus obtainingthe molded foam (see, for example, Patent Document 1, paragraph 0003).

CITATION LIST Patent Document

Patent Document 1: Japanese Patent Laid-Open No. Hei-11-343360

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

The molded foam manufactured as described above is light in weight andhas good moldability. In recent years, therefore, the molded foam hasbeen used as an interior material for vehicles or the like in many ofits applications.

For example, in some cases for the interior of the vehicle, a moldedfoam is used as a member constituting a floor for the purpose ofimproving the shock-absorbing effect against passenger's feet so thatthe riding comfort is high. More specifically, in some cases, a tibiapad, which is a molded foam, is interposed as an interior materialbetween a floor panel and a floor carpet. The tibia pad is ordinarily apad in a flat plate form having a flat surface. There is, therefore, apossibility of a force in a direction (sliding direction) along thesurface of the tibia pad (hereinafter, referred to as a moving force)being applied to the floor carpet (another material member), dependingon the motion of passenger's feet put on the floor carpet. When thecarpet receives such a force, there is a possibility of the floor carpetsliding easily on the flat surface of the tibia pad to shift in positionrelative to the tibia pad. There is, therefore, a need to fix the floorcarpet and the tibia pad to each other by using a double-sidedpressure-sensitive adhesive tape or the like, and the work of formingthe floor of the vehicle or the like is troublesome.

In some cases, the tibia pad is used in a state of having its surfacemaintained in contact with some of surrounding members, such as a frameconstituting the vehicle. In such a case, there is a possibility of thetibia pad and another member rubbing together to cause unusual noise dueto the vibration during travel of the vehicle, for example.

Therefore, a first object of the present invention is to provide amolded foam capable of effectively being prevented from shifting inposition relative to another member in contact with a surface of themolded foam when a force is applied to it in a direction of sliding onthe other member.

A second object of the present invention is to provide a molded foamcapable of effectively preventing its surface from being in contact witheach other and rubbing on another member to cause unusual noise.

Means for Solving Problems

A molded foam in a first aspect of the present invention provided toachieve the above-described first object is a molded foam formed byheating expandable resin particles filled into a foaming mold, themolded foam including a plurality of first ridges arranged in onedirection, and a plurality of second ridges arranged in anotherdirection and disposed so as to intersect the first ridges, the firstridges and the second ridges being provided on a surface of the moldedfoam.

With this arrangement, for example, when another member is placed on themolded foam, and when the other member receives an external force(moving force) in a sliding direction, the plurality of first ridgesarranged in one direction and the plurality of second ridges arranged inanother direction so as to intersect the first ridges can support themoving force. More specifically, the first ridges and the second ridgesare capable of maintaining a state of receiving the moving force in thesame attitude with stability without falling down. Accordingly, thefirst ridges and the second ridges produce an anchoring effect by beingbrought into suitable contact with the other member. In this way, theother member can be maintained in a state of being not easily slidableon the molded foam. Therefore, the other member does not easily shift inposition relative to the molded foam. The other member may be a membermade of a metal such as a metal sheet as well as a soft sheet (or mat).If the surface of the metal sheet is not completely smooth surface, thefirst ridges and the second ridges can produce an anchoring effect bybeing brought into suitable contact with the surface of the metal sheet.

In a molded foam in a second aspect of the present invention, to achievethe above-described second object, each of the first ridges and thesecond ridges has a sectional shape tapered toward its top.

In this arrangement, since each of the first ridges and the secondridges has a sectional shape tapered toward its top, it has flexibilityat least at the top side. Also, since each of the first ridges and thesecond ridges has a sectional shape tapered toward its top, the area ofcontact between the molded foam and the other member is reduced.Moreover, the first ridges and the second ridges are constructed so asto support each other by intersecting each other, there is nopossibility of the first ridges and the second ridges being largelydeformed from their base portions. Therefore, even when the molded foamand the other member receive a force such that they rub together,portions on the top sides of the first ridges and the second ridges aredeformed by following a relative small change in position between themolded foam and the other member. This means that sliding between thefirst ridges and the second ridges and the other member does not easilyoccur. As a result, it is possible to effectively prevent the occurrenceof unusual noise.

In the molded foam in accordance with the present invention, it ispreferable that the plurality of first ridges be arranged with aconstant pitch and the plurality of second ridges be arranged with aconstant pitch.

The arrangement of the first ridges and the second ridges with aconstant pitch ensures that when the molded foam and the other memberreceive a force such that they rub together, the force applied to thefirst ridges and the second ridges is evenly dispersed, thus furtherimproving the effect of preventing unusual noise.

In the molded foam in the second aspect of the present invention, thetapered shape may be formed so as to have a smoothly continuous contourin sections of the first ridges and the second ridges.

In the second molded foam in accordance with the present invention, thetapered shape may be formed so as to have an acute contour in sectionsof the first ridges and the second ridges.

Advantageous Effects of Invention

In the molded foam in the first aspect of the present invention, when aforce in a sliding direction is applied to the molded foam and the othermember in contact with the molded foam, the force can be supported bythe plurality of first ridges arranged in one direction and theplurality of second ridges arranged in another direction such as tointersect the first ridges. That is, the first ridges and the secondridges can receive the moving force in the same attitude with stabilitywithout falling down. In this way, the other member can effectively beprevented from shifting in position relative to the molded foam or themolded foam can effectively be prevented from shifting in positionrelative to the another member.

In the molded foam in the second aspect of the present invention, theplurality of first ridges arranged in one direction and the plurality ofsecond ridges arranged in another direction and disposed so as tointersect the first ridges' are provided on a surface of the moldedfoam, and the sectional shape of each of the first ridges and the secondridges is tapered toward its top, thereby ensuring that sliding cannoteasily occur between the first ridges and second ridges and the othermember. As a result, it is possible to effectively prevent theoccurrence of unusual noise.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a state immediately before a lid of atool box (a molded foam in a first embodiment) incorporated in a vehicleis closed.

FIGS. 2( a), 2(b), and 2(c) are enlarged views of an upper surface of aflange portion of the tool box; FIG. 2( a) is a perspective view; FIG.2( b) is a plan view; and FIG. 2( c) is a longitudinal sectional view.

FIGS. 3( a) and 3(b) show a foaming mold for forming the molded foam;FIG. 3( a) is a longitudinal sectional view; and FIG. 3( b) is a planview (bottom view) of an inside wall on the left.

FIG. 4 is a longitudinal sectional view of a lower portion of a vehiclehaving a tibia pad (a molded foam in a second embodiment).

FIGS. 5( a), 5(b), and 5(c) are longitudinal sectional views of moldedfoams in other embodiments.

FIGS. 6( a), 6(b), and 6(c) are longitudinal sectional views of foamingmolds (more specifically, left inside walls) for forming the moldedfoams shown in FIG. 5.

FIG. 7 is a plan view (bottom view) of a foaming mold in anotherembodiment in which the positions of passage holes are changed.

DESCRIPTION OF EMBODIMENTS

An embodiment of the present invention will be described with referenceto the drawings.

A molded foam is formed by filling expandable resin particles obtainedby preliminarily foaming resin particles into a foaming mold and thenheating the expandable resin particles. The ratio of expansion can bechanged as desired according to the purpose for which the molded foam isto be used. FIG. 1 shows a tool box 1 incorporated in a vehicle as anexample of the molded foam formed as described above. The tool box 1 hasa rectangular box body 5 having three storage portions 2, 3, and 4 andalso has an annular flange portion 6 formed on the upper end of the boxbody 5. The tool box 1 is supported by having the flange portion 6placed on an upper surface 9A of a U-shaped frame member 9 made of ametal and provided on the vehicle body side. The tool box 1 also has alid 7 in a plate form for covering the upper surface of the box body 5.A contact member 7A in an annular plate form, which is brought intocontact with the upper surface of the box body 5, is formed along anouter peripheral portion of the lid 7.

The molded foam can be made of any expandable resin material. It ispreferable that the molded foam be formed, for example, of athermoplastic resin among expandable resin materials. Examples of thethermoplastic resin are a polystyrene resin, a polyolefin resin (e.g., apolypropylene resin or a polyethylene resin), a polyester resin (e.g.,polyethylene terephthalate, polybutylene terephthalate or polyethylenenaphthalate), a polycarbonate resin, and a polylactic resin. It ispreferable to use a composite resin including polystyrene andpolyethylene among these resins as the expandable resin material.

On an outer peripheral (rectangular) upper surface 8A in the horizontalupper surface of the tool box 1, a plurality of first ridges 8T1projecting upward from the upper surface 8A and extending linearly in aleft-right direction, as shown in FIG. 1 and FIGS. 2( a), 2(b), and2(c). Further, on the upper surface 8A, a plurality of second ridges 8T2projecting upward from the upper surface 8A so as to have the sameheight as that of the first ridges 8T1 and extending linearly in afront-rear direction orthogonal to the first ridges 8T1. The pluralityof first ridges 8T1 are arranged in the front-rear direction with aconstant pitch P1 set therebetween. The plurality of second ridges 8T2are arranged in the left-right direction with a constant pitch P2 (P1=P2in the present embodiment) set therebetween. Each of the first ridges8T1 and the second ridges 8T2 has a sectional shape tapered toward itstop. More specifically, each of the first ridges 8T1 and the secondridges 8T2 is a generally triangular sectional shape having a sharpcontour (constituted by contour lines forming an acute angle).

Accordingly, the contact member 7A of the lid 7 is pressed against theupper surface 8A of the tool box 1 by the weight of the lid 7 when thelid 7 is closed. Thus, the contact member 7A can be stably supported bythe first ridges 8T1 and the second ridges 8T2. Since the sectionalshape of each of the first ridges 8T1 and the second ridges 8T2 isgenerally triangular, the area of contact between the first ridges 8T1and the second ridges 8T2 and the contact member 7A is small. Therefore,the first ridges 8T1 and the second ridges 8T2 can be brought intosuitable contact with the contact member 7A. An anchoring effect isthereby produced, such that the lid 7 on the tool box 1 does not easilymove relative to the tool box 1. Prevention of the occurrence of unusualnoise by rubbing between the contact member 7A and the tool box 1 isalso enabled.

In general, the mechanism of generation of unusual noise (sounding) (themechanism of sounding) is explained by a stick-slip phenomenon. Thestick-slip phenomenon is a phenomenon in which when two objects in astate of being pressed against each other under a load move relative toeach other while being maintained in contact with each other, stickingand sliding alternately occur between the surfaces of the objects toreduce the smoothness of relative movement between the two objects. Whensuch a phenomenon occurs, vibration (frictional vibration) occurs in theobjects and a sounding phenomenon appears. That is, it is thought thatone of the objects repeats moving little by little by alternatingsliding over and sticking to the other object (counterpart) to generatesound. The first ridges 8T1 and the second ridges 8T2 are markedlyeffective on such a phenomenon. Because avoidance of such a phenomenonis enabled, it is possible to prevent one of the objects from shiftingin position relative to the other.

If the two objects are molded foams light in weight and having highfrictional coefficients, unusual noise can be easily caused by vibrationor the like. Among molded foams, one foamed at a higher expansion ratiocan produce unusual noise more easily. In a case where the molded foamformed of such a soft material has a rectangular contact surface in adirection orthogonal to the direction along which the objects rubtogether, a corner portion in a position on the front side in therubbing direction in the contact surface has a higher frictionalresistance and can easily be a cause of unusual noise by rubbing. Thefirst ridges 8T1 and the second ridges 8T2 are also markedly effectiveon the occurrence of unusual noise in such a case.

That is, the first ridges 8T1 and the second ridges 8T2 each have atapered sectional shape, and therefore have flexibility at least at thetop side and a reduced area of contact with the contact member 7A.Moreover, since the first ridges 8T1 and the second ridges 8T2 areconstructed so as to support each other by intersecting each other,there is no possibility of the first ridges 8T1 and the second ridges8T2 being largely deformed from their base portions. Therefore, evenwhen the tool box 1 and the lid 7 receive a force such that they rubtogether, portions on the top sides of the first ridges 8T1 and thesecond ridges 8T2 are deformed by following a relative change inposition between the first ridges 8T1 and the second ridges 8T2 and thecontact member 7A. This means that sliding between the first ridges 8T1and the second ridges 8T2 does not easily occur. As a result, it ispossible to effectively prevent the occurrence of unusual noise.

In particular, by forming the plurality of first ridges 8T1 and theplurality of second ridges 8T2 such that the first ridges 8T1 and thesecond ridges 8T2 extend orthogonal to each other as described above,the annular (rectangular) frame portion surrounded on all sides areformed so as to be continuous along the front-rear and left-rightdirections. The shape-maintaining strength of the first ridges 8T1 andthe second ridges 8T2 can be improved in this way. Thus, furthereffectiveness in preventing unusual noise and in preventing a shift inposition is ensured.

The ratio of the area of the region in which the above-described firstridges 8T1 and the second ridges 8T2 are formed (ridge formation region)to the total area of the outer periphery of the upper surface 8A of thetool box 1 (the proportion of the ridge formation region in a unit area)is preferably 80% or less, more preferably 50% or less. By setting thearea in such proportion, the effect of preventing positional shifting orpositional displacement, not to mention the effect of preventing unusualnoise, is further improved.

First ridges 8T1 and second ridges 8T2 may also be formed on a lowersurface 6A of the flange portion 6. In such a case, the tool box 1 canbe prevented from being moved relative to the frame member 9 made ofmetal, for example, by vibration or the like during travel of thevehicle. Prevention of the generation of unusual noise caused by rubbingbetween the lower surface 6A of the flange portion 6 and the uppersurface 9A of the frame member 9 is thereby enabled. First ridges 8T1and second ridges 8T2 may also be formed on a lower surface 5A of thebox body 5 that is brought into contact with a vehicle constituentmember 10 indicated by the double-dot-dash line in FIG. 1. In such acase, the tool box 1 can be prevented from being moved relative to thevehicle constituent member 10 by vibration or the like during travel ofthe vehicle. Prevention of the generation of unusual noise caused byrubbing between the lower surface 5A of the box body 5 and the vehicleconstituent member 10 is thereby enabled.

The first ridges 8T1 and the second ridges 8T2 are low ridges having aheight of 1 mm or less. In FIG. 1, therefore, the first ridges 8T1 andthe second ridges 8T2 are indicated by lines. In FIGS. 2( a), 2(b) and2(c), the first ridges 8T1 and the second ridges 8T2 are illustrated inenlarged diagrams in order to clearly show the shapes of the firstridges 8T1 and the second ridges 8T2.

In some cases, in the surface of the tool box 1, which is a molded foamformed by heating expandable resin particles filled into a mold (moldingspace), a tortoise-shell pattern occurs, for example, clue to variationsin particle size and foaming density of the expandable resin particles.Even in a case where such a tortoise-shell pattern occurs, thetortoise-shell pattern can be made inconspicuous by forming the firstridges 8T1 and the second ridges 8T2 on the upper surface of the toolbox 1 (molded foam) as described above. The tool box 1 can be improvedin design in this way, thus improving the commodity value. Even in acase where the surface of the tool box 1 (molded foam) is scratched,scratches can be made inconspicuous, because they are cancelled out bythe first ridges 8T1 and the second ridges 8T2. For the purpose ofachieving these effects, first ridges 8T1 and second ridges 8T2 may beformed on other portions of the above-described tool box 1 where nofirst ridges 8T1 and no second ridges 8T2 are formed.

FIGS. 3( a) and 3(b) show a foaming mold 11 (hereinafter, simplyreferred also to as a “mold”) for forming the molded foam. The foamingmold 11 has a pair of mold bodies 12 and 13 as divided parts on the leftand right. An inside wall (molding tool) 12A constituting the mold body12 on the left-hand side and an inside wall (molding tool) 13Aconstituting the mold body 13 on the right-hand side are disposedopposite to each other. By fitting the front sides (opposed sides) ofthe left and right inside walls 12A and 13A to each other, a moldingspace to be filled with expandable resin particles is formed in the mold11. The mold 11 shown in FIG. 3( a) is a lateral-type mold having a pairof mold bodies 12 and 13 openable and closable along a left-rightdirection (horizontal direction). The mold 11, however, mayalternatively be a vertical-type mold having a pair of mold bodies 12and 13 openable and closable along a top-bottom direction. Also, whilethe right inside wall 13A is provided in a plate form as shown in FIG.3( a), it may alternatively be provided as the same box-type inside wallas the left inside wall 12A. In such a case, a molding space may beformed so that the first and second ridges 8T1 and 8T2 described beloware formed on each of the upper and lower surfaces of a molded foam.

The left mold body 12 has the above-described inside wall 12A in a boxform opened on the right-hand side and a back plate 12B for forming aheating and cooling chamber 12 a by covering the back side of the insidewall 12A. The right mold body 13 has the above-described inside wall 13Ain a plate form and a back plate 13B for forming a heating and coolingchamber 13 a by covering the back side of the inside wall 13A.

Portions of a steam supply pipe 21, a cooling water supply pipe 22 and acompressed air supply pipe 23 on one end (lower end) sides of thesepipes are fixed in an upper plate portion 12 b of the back plate 12B ofthe left mold body 12 in a state of being passed through the plateportion while being spaced apart from one another by a predetermineddistance. The portions of the steam supply pipe 21, the cooling watersupply pipe 22 and the compressed air supply pipe 23 on the one end(lower end) sides are thereby maintained in a state of being inserted inthe heating and cooling chamber 12 a. Opening and closing valves 21V,22V and 23V are provided at intermediate positions in the steam supplypipe 21, the cooling water supply pipe 22 and the compressed air supplypipe 23. The cooling water supply pipe 22 has an extension portion 22Aextending from the upper plate portion 12 b to the vicinity of a lowerplate portion 12 c described below. Openings 22 a through which coolingwater is supplied are formed in the extension portion 22A atpredetermined intervals along the direction of extension. A steam supplypipe 21, a cooling water supply pipe 22 and a compressed air supply pipe23, not shown in the figure, are also fixed on the right mold body 13.Opening and closing valves 21V, 22V, and 23V are also provided atintermediate positions in these pipes, the steam supply pipe 21, coolingwater supply pipe 22 and compressed air supply pipe 23.

Portions on one end (upper end) sides of a drain pipe 24 and a vacuumsupply pipe 25 connected to a vacuum unit are fixed in the lower plateportion 12 c of the back plate 12B of the left mold body 12 in a stateof being passed through the plate portion while being spaced apart fromeach other by a predetermined distance. Opening and closing valves 24Vand 25V are provided at intermediate positions in the drain pipe 24 andthe vacuum supply pipe 25. A drain pipe 24 and a vacuum supply pipe 25,not shown in the figure, are also fixed on the right mold body 13.Opening and closing valves 24V and 25V are also provided in these pipes,the drain pipe 24 and vacuum supply pipe 25.

The left inside wall 12A will be described in detail. A plurality offirst groove portions M1 continuously extending along one direction(more specifically, along the top-bottom direction) in a predeterminedplace (hereinafter, also referred to as an “intended area”) in a formingsurface 12K of the inside wall 12A. In the intended area, a plurality ofsecond groove portions M2 continuously extending along another direction(more specifically, along the front-rear direction) orthogonal to thefirst groove portions M1 are formed with the same depth (height) as thefirst groove portions M1. The “front-rear direction” refers to adirection orthogonal to the left-right direction and the top-bottomdirection.

The plurality of first groove portions M1 are arranged in the front-reardirection with a constant pitch P1 set therebetween (see FIG. 3( b)).The plurality of second groove portions M2 are arranged in thetop-bottom direction with a constant pitch P2 (P1=P2 in the presentembodiment) set therebetween (see FIG. 3( b)). It is preferable todetermine the pitches between the plurality of first groove portions M1and the plurality of first groove portions M2 so that the coolingefficiency is improved. Needless to say, the pitches are not necessarilyconstant between all the groove portions. Also, while the first grooveportions M1 and the second groove portions M2 are orthogonal to eachother in the present embodiment, forming the first groove portions M1and the second groove portions M2 such that the first groove portions M1and the second groove portions M2 extend in different directions inorder to improve the cooling efficiency or the like may suffice. Forexample, the first groove portions M1 and the second groove portions M2may be formed so as to intersect each other not orthogonal butobliquely, depending on the shape of the molded article (molded foam).

The intended area is determined only on the forming surface 12K of theleft inside wall 12A in the arrangement shown in FIG. 1. However, thepresent invention is not limited to this. For example, not only the wallsurface (forming surface 12K) opposed to the right mold body 13 but alsoupper and lower wall surfaces opposed along the top-bottom direction inthe wall surfaces forming the molding space in the inside wall 12A shownin FIG. 1 may be determined as intended areas. Also, front and rear wallsurfaces opposed to each other in the front-rear direction of the insidewall 12A may be determined as intended areas. It is preferable that inorder to improve the cooling efficiency or the like, the first grooveportions M1 and the second groove portions M2 be formed through theentire areas between ends of the wall surfaces determined as intendedareas so as to connect the ends. Furthermore, the ends of the firstgroove portions M1 and the second groove portions M2 formed in theintended area on the above-described one wall surface and the ends ofthe first groove portions M1 and the second groove portions M2 formed inthe intended areas on the other wall surfaces may be continuous witheach other or may not be continuous with each other. Expandable resinparticles S are filled into the molding space formed by the left andright inside walls 12A and 13A thus constructed, and are heated, therebyforming a molded foam. A plurality of first ridges 8T1 and a pluralityof second ridges 8T2 (see FIGS. 2( a), 2(b) and 2(c)) are formed on theformed molded foam so as to project.

Passage holes for supplying the molding space (cavity) with steam orcooling water (or cooling air) introduced into the above-describedheating and cooling chamber 12 a by means of the steam supply pipe 21,the cooling water supply pipe 22, the compressed air supply pipe 23 andthe drain pipe 24 are formed in the left inside wall 12A. Morespecifically, first passage holes 12K1 are formed in the bottom surfacesof the first groove portions M1 of the inside wall 12A, and secondpassage holes 12K2 are formed in the bottom surfaces of the secondgroove portions M2 of the inside wall 12A. The first passage holes 12K1are respectively formed in the first groove portions M1. The firstpassage holes 12K1 are thus formed by setting the constant pitch P1 inthe front-rear direction, similarly to the first groove portions M1. Onthe other hand, the second passage holes 12K2 are respectively formed inthe second groove portions M2. The second passage holes 12K2 are thusformed by setting the constant pitch P2 in the top-bottom direction,similarly to the second groove portions M2. The shape of each of thefirst and second passage holes 12K1 and 12K2 may be circular, ellipticalor rectangular, for example. Each of the first and second passage holes12K1 and 12K2 may alternatively be in the form of a longitudinal slit.While the only one first passage hole 12K1 and the only one secondpassage hole 12K2 are formed in each of the first and second grooveportions M1 and M2 in the present embodiment, two or more passage holesmay be formed in each of the first and second groove portions M1 or M2.One or more first passage holes 12K1 may be formed in every other orevery third first groove portions M1 instead of being formed in eachfirst groove portion M1. One or more first passage holes 12K1 mayalternatively be formed in particular ones of the first groove portionsM1 that are randomly selected. Similarly, one or more second passageholes 12K2 may be formed in every other or every third second grooveportions M2. One or more second passage holes 12K2 may alternatively beformed in particular ones of the second groove portions M2 that arerandomly selected. Needless to say, passage holes may be formed atpoints of intersection of the first groove portions M1 and the secondgroove portions M2. In some cases, the diameter of the first passageholes 12K1 or the second passage holes 12K2 is larger than the width ofthe first groove portions M1 or the second groove portions M2 or thepitch between the first groove portions M1 or between the second grooveportions M2. In such cases, forming part of either first passage hole12K1 or second passage hole 12K2 inside at least one of the first grooveportion M1 and the second groove portion M2 suffices. The positions ofthe first and second passage holes 12K1 and 12K2 relative to the firstand second groove portions M1 and M2 may be regularly set, for example,by setting the constant pitch P2 as described above, or randomly set.Needless to say, at least passage holes may be regularly or randomlyformed in the inside wall 13A in the right mold body 13.

The depths of the first groove portions M1 and the second grooveportions M2 are preferably 1 mm or less, more preferably 0.3 mm or less.The pitch P1 between the first groove portions M1 and the pitch P2between the second groove portions M2 are preferably 2 mm to 50 mm, morepreferably 30 mm or less (excluding zero). By setting the pitches P1 andP2 as described above, the releasability of the molded foam from themold 11 (more specifically, the left inside wall 12A) can be improved.All the plurality of first and second groove portions M1 and M2 may beequal in depth to each other or different in depth from each other, oronly part of the first and second groove portions M1 and M2 may bedifferent in depth from the others. All the plurality of first andsecond groove portions M1 and M2 may be equal in width to each other ordifferent in width from each other, or only part of the first and secondgroove portions M1 and M2 may be different in width from the others.

The method of making the mold 11 (more specifically, the left insidewall 12A) are not restrictively specified. Machining and any othermethod may be used for making the mold 11. Since the depths of the firstgroove portions M1 and the second groove portions M2 are small asdescribed above, it is preferable to use etching as the method of makingthe mold 11 (more specifically, the left inside wall 12A). Use of such aworking method ensures that the forming surfaces of the mold havingcomplicated shapes can be formed with accuracy, in addition to theimproved design freedom.

The process of forming a molded foam by using the mold 11 constructed asdescribed above will be described mainly with respect to the left moldbody 12. The mold 11 shown in FIG. 3 is a concept illustration forexplaining the first groove portions M1, the second groove portions M2,the first passage holes 12K1 and the second passage holes 12K2 and doesnot conform in configuration to a molded foam described below.

First, the front sides (opposed sides) of the left and right insidewalls 12A and 13A are fitted to each other. The molding space is formedby the left and right inside walls 12A and 13A. Expandable resinparticles S are filled into the formed molding space by using a fillingdevice not shown in the figure. Next, steam is supplied from the leftsteam supply pipe 21 to the left heating and cooling chamber 12 a bysetting the left opening and closing valve 21V to the open state. Atthis time, the drain pipe (not shown) in the right mold body 13 isopened. The steam supplied to the left heating and cooling chamber 12 aheats the outer surface of the left inside wall 12A and is supplied tothe molding space through the first and second passage holes 12K1 and121(2 in the inside wall 12A. The steam supplied to the molding space isled to the outside (heating and cooling chamber 13 a) of the rightinside wall 13A through the passage holes (not shown) in the inside wall13A. The steam introduced into the heating and cooling chamber 13 a inthe mold body 13 is discharged out of the right mold body 13 through thedrain pipe in the right mold body 13 (not shown) in the mold body 13. Bythis first heating step, the expandable resin particles S filled intothe molding space are evenly heated. Next, the left opening and closingvalve 21V is closed and the left drain pipe 24 is opened. Also, thedrain pipe (not shown) in the right mold body 13 is closed and the rightopening and closing valve (not shown) is opened. Steam is then suppliedfrom the steam supply pipe (not shown) to the right heating and coolingchamber 13 a. The steam supplied to the heating and cooling chamber 13 aheats the outer surface of the right inside wall 13A and is supplied tothe molding space through the passage holes (not shown) in the insidewall 13A. The steam supplied to the molding space is led to the outside(heating and cooling chamber 12 a) of the left inside wall 12A throughthe first and second passage holes 12K1 and 121(2 in the inside wall12A. The steam introduced into the heating and cooling chamber 12 a inthe left mold body 12 is discharged out of the mold body 12 through thedrain pipe 24 in the left mold body 12. By this second heating step, theexpandable resin particles S filled into the molding space are evenlyheated. After heating, the right opening and closing valve (not shown)is closed and the left drain pipe 24 is closed. A third heating step isthereafter performed. In the third heating step, in a state where thedrain pipes 24 in the two mold bodies 12 and 13 (the drain pipe in theright mold body 13 is not shown) are closed, the opening and closingvalves 21V on the two mold bodies 12 and 13 (the opening and closingvalve on the right mold body 13 is not shown) are opened and steam issupplied to the heating and cooling chambers 12 a and 13 b. The suppliedsteam heats the outer surfaces of the left and right inside walls 12Aand 13A and is supplied to the molding space through the first andsecond passage holes 12K1 and 12K2 in the left inside wall 12A and thepassage holes (not shown) in the right inside wall 13A. Thereby, theexpandable resin particles S filled into the molding space are againheated.

After the completion of heating, the opening and closing valves 22V onthe two mold bodies 12 and 13 (the right opening and closing valve isnot shown) are opened. Cooling water is then sprayed from the openings22 a of the extension portion 22A to the left and right inside walls 12Aand 13A, thereby cooling the left and right inside walls 12A and 13A. Atthis time, part of the cooling water enters the space between the leftand right inside walls 12A and 13A (i.e., the molding space) by passingthrough the first and second passage holes 12K1 and 12K2 in the leftinside wall 12A and the passage holes in the right inside wall 13A.Therefore, cooling of the molded foam is promoted. The molded foamstarts shrinking by being cooled. Gaps are thereby formed between themolded foam and the left and right inside walls 12A and 13A. The coolingwater can spread easily over the intended areas by flowing into thefirst groove portions M1 and the second groove portions M2 through thesegaps, thus improving the cooling efficiency of the molded foam.

After the completion of cooling with the cooling water, the opening andclosing valves 23V on the two mold bodies 12 and 13 (the right openingand closing valve is not shown) are opened. Compressed air is thensupplied from the compressed air supply pipes 23 to the heating andcooling chambers 12 a and 13 a. The compressed air supplied to theheating and cooling chambers 12 a and 13 a is supplied to the moldingspace through the first and second passage holes 12K1 and 12K2 and thepassage holes in the right inside wall 13A. The compressed air suppliedto the molding space leads the cooling water remaining in the leftinside wall 12A to the first and second passage holes 12K1 and 12K2 andthe passage holes in the right inside wall 13A by passing through thegaps between the molded foam and the left and right inside walls 12A and13A. The cooling water is thereby discharged to the outsides (heatingand cooling chambers 12 a and 13 a) of the inside walls 12A and 13Athrough the first and second passage holes 12K1 and 12K2 and the passageholes in the right inside wall 13A. The cooling water discharged intothe heating and cooling chambers 12 a and 13 a is discharged out of theleft and right mold bodies 12 and 13 through the left and right drainpipes 24. This compressed air also has a role of cooling the left andright inside walls 12A and 13A and the molded foam.

Subsequently, a decompression cooling step is performed. In thedecompression cooling step, the opening and closing valves 24V in thedrain pipes 24 in the two mold bodies 12 and 13 (the right opening andclosing valve is not shown) are closed and the opening and closingvalves 25V (the right opening and closing valve is not shown) arethereafter opened. The interiors of the heating and cooling chambers 12a and 13 a are then decompressed by means of the vacuum supply pipes 25.Water remaining in the heating and cooling chambers 12 a and 13 a, andmoisture attached to or contained in the molded foam formed are therebyevaporated, thereby completing the decompression cooling step. At thistime, cooling of the molded foam is promoted by using evaporation latentheat accompanying the evaporation of water. Thereafter, the mold 11 isopened by separating the left and right inside walls 12A and 13A, andthe left and right opening and closing valves 23V (the right opening andclosing valve is not shown) are opened. Compressed air for mold releaseis then supplied from the left and right compressed air supply pipes 23(the right compressed air supply pipe is not shown) to the heating andcooling chambers 12 a and 13 a. The compressed air is thereby suppliedto the gaps between the left and right inside walls 12A and 13A and themolded foam through the first and second passage holes 12K1 and 12K2 andthe passage holes in the right inside wall 13A (the right passage holesare not shown), thereby releasing the molded foam from the left andright inside walls 12A and 13A. The process is completed by taking themolded foam out of the space between the left and right inside walls 12Aand 13A. Needless to say, mold release pins may be provided in the moldand used together with compressed air to release and take out the moldedfoam. Also, the molded foam may be released and taken out only with therelease pins.

In the mold 11 in the present embodiment, as described above, the firstgroove portions M1 are continuously formed from one end of the intendedarea on the forming surface of the left inside wall 12A to the other endalong the top-bottom direction, while the second groove portions M2 arecontinuously formed from one end of the intended area on the mold 11 tothe other end along the front-rear direction. Also, the first and secondpassage holes 12K1 and 12K2 are used as inlet and outlet holes forsupplying steam for heating expandable resin particles or cooling water(or cooling air) for cooling the molded foam immediately after foamingto the interior of the mold. With these arrangements, steam or coolingwater supplied through the first passage holes 12K1 and the secondpassage holes 12K2 is enabled to easily spread over the intended area onthe forming surface via the first and second groove portions M1 and M2continuously formed. Moreover, steam or cooling water is uniformlysupplied in every direction along the forming surface. Therefore, themoldability and the cooling efficiency can be improved.

Water produced by cooling of steam in the molding space during thecooling step and cooling water will remain in the molding space. Theremaining water and cooling water are speedily discharged out of themolding space with reliability through the first passage holes 12K1 andthe second passage holes 12K2 formed in correspondence with the firstgroove portions M1 and the second groove portions M2. Thus, accumulationof water in the mold 11 (more specifically, in the mold body 12) can beprevented to avoid hindrance to filling of expandable resin particles bywater accumulated in the mold 11 (more specifically, in the moldingspace) at the time of next foaming step. Therefore, the fillingoperation can be performed with reliability and the moldability can beimproved. Since the problem of accumulation of water in the mold 11(mold body 12) is avoided, a process of cooling with cooling water canbe positively adopted. As a result, the cooling efficiency is improvedand cycle-up can be achieved by a time reduction effect.

Furthermore, the first passage holes 12K1 and the second passage holes12K2 are used for supplying compressed air for releasing the formedmolded foam from the left inside wall 12A. Since the first and secondpassage holes 12K1 and 12K2 are formed in the first and second grooveportions M1 and M2, compressed air can be supplied directly to the firstand second groove portions M1 and M2, thereby enabling the compressedair to be easily delivered uniformly to the intended areas on theforming surfaces through the first and second groove portions M1 and M2,and enabling mold release to be smoothly performed. Moreover, because ofthe arrangement enabling compressed air to flow into the first andsecond groove portions M1 and M2 which extend in different directions,compressed air can be dispersed uniformly along the surface of themolded foam in contact with the left inside wall 12A at the time ofrelease of the molded foam from the mold after foaming, thus enablingthe molded foam to be released more smoothly.

The molded foam formed by foaming with the mold 11 constructed asdescribed above can be used as a tibia pad 14 to be provided on a fontseat floor of a vehicle as shown in FIG. 4 (or can be used as a floorspacer provided on a vehicle rear seat floor). The tibia pad 14 isplaced between a floor panel 15 and a floor carpet placed as an interiormember on the floor panel 15. The tibia pad 14 placed in this way isintended to improve the shock-absorbing effect against passenger's feet17 so that the riding comfort is high.

The above-described tibia pad 14 is constituted by a molded foam formedby heating expandable resin particles so that the resin particles arefoamed into a foam in a plate form. The tibia pad 14 has a plurality offirst ridges 14T1 projecting upward from its upper surface 14A andextending straight along a left-right direction. The tibia pad 14 alsohas a plurality of second ridges 14T2 projecting upward from its uppersurface 14A to the same height as that of the first ridges 14T1 andextending straight along a front-rear direction orthogonal to the firstridges 14T1. The plurality of first ridges 14T1 are arranged in thefront-rear direction with a constant pitch P3 set therebetween. Thepitch P3 may be the same as the constant pitch P1 shown in FIG. 2( b) ordifferent from the pitch P1. Also, the plurality of second ridges 14T2are arranged in the left-right direction with a constant pitch settherebetween. The pitch between the second ridges 14T2 may be the sameas the constant pitch P3 between the first ridges 14T1 or different fromthe pitch P3. Each of the first ridges 14T1 and the second ridges 14T2has a sectional shape tapered toward its top, more specifically, agenerally triangular sectional shape.

The thus formed tibia pad 14 is placed between the floor panel 15 andthe floor carpet 16. The tibia pad 14 is thereby enabled to stablysupport, for example, a load received by the floor carpet 16 from thepassenger's feet 17, by its first ridges 14T1 and the second ridges14T2, when the passenger gets into the vehicle. The first ridges 14T1and the second ridges 14T2 are thereby brought into suitable contactwith the floor carpet 16 to enable effective prevention of theoccurrence of unusual noise. Moreover, the floor carpet 16 is stabilizedagainst movement relative to the tibia pad 14, so that the floor carpet16 can also be prevented from shifting in position relative to the tibiapad 14. While the first ridges 14T1 and the second ridges 14T2 areformed only on the front surface of the tibia pad 14 (the surface to bebrought into contact with the floor carpet 16) in the arrangement shownin FIG. 4, first ridges 14T1 and second ridges 14T2 may also be formedon the back surface of the tibia pad 14 (the surface to be brought intocontact with the floor panel 15).

The present invention is not limited to the above-described embodiments.Various changes can be made in the described embodiments withoutdeparting from the scope of the gist of the invention.

While an interior member (tibia pad 14) incorporated in a vehicle hasbeen described in the above-described embodiment as a molded foam, anobject such as an ornamental, a sofa or a bed placed in a room, acushioning member placed under a floor, or the like other than interiormembers incorporated in a vehicle may be constituted by a molded foam inaccordance with the present invention.

In the above-described embodiments, each of the first ridges and thesecond ridges of the molded foam has a triangular sectional shapetapered toward its top. However, each ridge may have any other shape.For example, each ridge may have a round shape with no angular corner atthe top. More specifically, ridges 18T1 and 18T2 may have a shapeprojecting in a curved form from a surface of a molded foam, as shown inFIG. 5( a), that is, has a semicircular shape. Ridges 19T1 and 19T2 mayalso have a base portion 19T21 having two surfaces rising from a surfaceof a molded foam in parallel to each other and perpendicular to thesurface of the molded foam, as shown in FIG. 5( b), that is, has theupper half of an oval shape. Ridges 20T1 and 20T2 may also have a shapeprojecting from a surface of a molded foam while being smoothly curved,as shown in FIG. 5( c), that is, has the upper half of an ellipticalshape. Thus, each ridge formed in this way has a tapered shape having asmoothly continuous contour (formed by a smoothly continuous contourline). While each ridge has a tapered shape in the above-describedembodiments, the shape of each ridge is not limited to such a taperedshape. Each ridge may have a non-tapered shape. For example, each ridgemay have a rectangular sectional shape (having four angular corners atthe top) constant in width in the top-bottom direction (in other words,between the tip and the base). Also, for example, when base portionseach having two surfaces rising from a surface of a molded foam areprovided in addition to the configurations shown in FIGS. 5, anarrangement may be provided in which the top (upper end) of one of thetwo surfaces is increased in height relative to the top (upper end) ofthe other, and the tops differing in height are connected to form aslanting surface. An arrangement in which the above-described taperedshape is provided on each of the tops (upper ends) of the two surfacesdiffering in height may alternatively be provided. The surfaces of thebase portion may be perpendicular to the surface of the molded foam ormay be formed as slanting surfaces rising toward a center of the ridge.A tapered shape stepped from the base portions may alternatively beprovided.

FIGS. 6( a), 6(b) and 6(c) show molds (more specifically, left insidewalls 12A) for forming the molded foams shown in FIGS. 5( a), 5(b) and5(c). That is, FIG. 6( a) shows a mold (more specifically, a left insidewall 12A) for molding the molded foam shown in FIG. 5( a). In such aninside wall, semicircular groove portions M3 and M4 are formed. FIG. 6(b) shows a mold (more specifically, a left inside wall 12A) for moldingthe molded foam shown in FIG. 5( b). In such an inside wall, grooveportions M5 and M6 each having a shape corresponding to the upper halfof the oval shape are formed. FIG. 6( c) shows a mold (morespecifically, a left inside wall 12A) for molding the molded foam shownin FIG. 5( c). In such an inside wall, groove portions M7 and M8 eachhaving a shape corresponding to the upper half of the elliptical shapeare formed.

In the above-described embodiments, the first ridges 8T1 are arrangedwith a constant pitch and the second ridges 8T2 are also arranged with aconstant pitch. However, the invention may be implemented by setting oneor both of the first and second ridges 8T1 and 8T2 with irregularpitches.

In the above-described embodiments, each of the first ridges 8T1 and thesecond ridges 8T2 is linearly formed. However, each ridge mayalternatively be constructed in a continuous zigzag form or in acontinuous curved form. Also, the first ridges 8T1 and the second ridges8T2 may be formed so as to intersect each other at a predetermined angledifferent from 90 degrees instead of being formed so as to orthogonallyintersect each other.

In the above-described embodiments, the first passage holes 12K1 areformed in the first groove portions M1, while the second passage holes12K2 are formed in the second groove portions M2. However, passage holes12K3 may be formed in portions other than the first groove portions M1and the second groove portions M2, as shown in FIG. 7. Morespecifically, passage holes 12K3 may be formed in portions at the middle(not necessarily at the middle) between each adjacent pair of the firstgroove portions M1 and at the middle (not necessarily at the middle)between each adjacent pair of the second groove portions M2. Furtherspecifically, passage holes 12K3 may be formed at centers (notnecessarily at centers) of flat surface portions 1211, each being formedby being surrounded on all sides by the first groove portions M1 and thesecond groove portions M2. While passage holes 12K3 are formed in allthe flat surface portions 1211 surrounded on all sides, passage holes12K3 may be formed only in particular ones of the flat surface portions1211. A mold having the passage holes 12K shown in FIG. 7 in addition tothe first passage holes 12K1 and the second passage holes 12K2 shown inFIG. 3 may be provided.

Reference Signs List

1 Tool Box

2, 3, 4 Storage Portion

5 Box Body

5A Lower Surface of Box Body

6 Flange Portion

6A Lower Surface of Flange Portion

7 Lid

7A Contact Member of Lid

8A Upper Surface of Tool Box

8T1 First Ridge

8T2 Second Ridge

9 Frame Member

9A Upper Surface of Frame Member

10 Vehicle Constituent Member

11 Foaming Mold

12, 13 Mold Body

12A, 13A Inside Wall

12H Flat Surface Portion

12K Forming Surface

12K1, 12K2, 12K3 Passage Hole

12 a, 13 a Heating and Cooling Chamber

14 Tibia Pad

14A Tibia Pad Upper Surface

14T1 First Ridge

14T2 Second Ridge

15 Floor Panel

16 Floor Carpet

17 Foot

18T1, 18T2, 19T1, 19T2, 20T1, 20T2 Ridge

M1 First Groove Portion

M2 Second Groove Portion

M3 to M8 Groove Portion

S Expandable Resin Particle

1. A molded foam formed by heating expandable resin particles filledinto a foaming mold, the molded foam comprising: a plurality of firstridges arranged in one direction, and a plurality of second ridgesarranged in another direction and disposed so as to intersect the firstridges, the first ridges and the second ridges being provided on asurface of the molded foam.
 2. The molded foam according to claim 1,wherein the plurality of first ridges are arranged with a constantpitch, and the plurality of second ridges are arranged with a constantpitch.
 3. A molded foam formed by heating expandable resin particlesfilled into a foaming mold, the molded foam comprising: a plurality offirst ridges arranged in one direction, and a plurality of second ridgesarranged in another direction and disposed so as to intersect the firstridges, the first ridges and the second ridges being provided on asurface of the molded foam, each of the first ridges and the secondridges having a sectional shape tapered toward its top.
 4. The moldedfoam according to claim 3, wherein the plurality of first ridges arearranged with a constant pitch, and the plurality of second ridges arearranged with a constant pitch.
 5. The molded foam according to claim 3,wherein the tapered shape has a smoothly continuous contour in sectionsof the first ridges and the second ridges.
 6. The molded foam accordingto claim 3, wherein the tapered shape has an acute contour in sectionsof the first ridges and the second ridges.
 7. The molded foam accordingto claim 4, wherein the tapered shape has a smoothly continuous contourin sections of the first ridges and the second ridges.
 8. The moldedfoam according to claim 4, wherein the tapered shape has an acutecontour in sections of the first ridges and the second ridges.